In vitro activation of human leukocytes in response to contact with synthetic hernia meshes

Comparative long-term effectiveness between ventral hernia repairs with biosynthetic and synthetic mesh

BACKGROUND

Debate exists regarding the most appropriate type of mesh to use in ventral hernia repair (VHR). Meshes are broadly categorized as synthetic or biologic, each mesh with individual advantages and disadvantages. More recently developed biosynthetic mesh has characteristics of both mesh types. The current study aims to examine long-term follow-up data and directly compare outcomes-specifically hernia recurrence-of VHR with biosynthetic versus synthetic mesh.

METHODS

With IRB approval, consecutive cases of VHR (CPT codes 49,560, 49,561, 49,565, and 49,566 with 49,568) performed between 2013 and 2018 at a single institution were reviewed. Local NSQIP data was utilized for patient demographics, perioperative characteristics, CDC Wound Class, comorbidities, and mesh type. A review of electronic medical records provided additional variables including hernia defect size, postoperative wound events to six months, duration of follow-up, and incidence of hernia recurrence. Longevity of repair was measured using Kaplan-Meier method and adjusted Cox proportional hazards regression.

RESULTS

Biosynthetic mesh was used in 101 patients (23%) and synthetic mesh in 338 (77%). On average, patients repaired using biosynthetic mesh were older than those with synthetic mesh (57 vs. 52 years; p = .008). Also, ASA Class ≥ III was more common in biosynthetic mesh cases (70.3% vs. 55.1%; p = .016). Patients repaired with biosynthetic mesh were more likely than patients with synthetic mesh to have had a prior abdominal infection (30.7% vs. 19.8%; p = .029). Using a Kaplan-Meier analysis, there was not a significant difference in hernia recurrence between the two mesh types, with both types having Kaplan Meir 5-year recurrence-free survival rates of about 72%.

CONCLUSION

Using Kaplan-Meier analysis, synthetic mesh and biosynthetic mesh result in comparable hernia recurrence rates and surgical site infection rates in abdominal wall reconstruction patients with follow-up to as long as five years.

Anti-inflammatory coating of hernia repair meshes: a 5-rabbit study

PURPOSE

Polymeric mesh implantation has become the golden standard in hernia repair, which nowadays is one of the most frequently performed surgeries in the world. However, many biocompatibility issues remain to be a concern for hernioplasty, with chronic pain being the most notable post-operative complication. Oxidative stress appears to be a major factor in the development of those complications. Lack of material inertness in vivo and oxidative environment formed by inflammatory cells result in both mesh deterioration and slowed healing process. In a pilot in vivo study, we prepared and characterized polypropylene hernia meshes with vitamin E (α-tocopherol)-a potent antioxidant. The results of that study supported the use of vitamin E as potential coating to alleviate post-surgical inflammation, but the pilot nature of the study yielded limited statistical data. The purpose of this study was to verify the observed trend of the pilot study statistically.

METHODS

In this work, we conducted a 5-animal experiment where we have implanted vitamin E-coated and uncoated control meshes into the abdominal walls of rabbits. Histology of the mesh-adjacent tissues and electron microscopy of the explanted mesh surface were conducted to characterize host tissue response to the implanted meshes.

RESULTS

As expected, modified meshes exhibited reduced foreign body reaction, as evidenced by histological scores for fatty infiltrates, macrophages, neovascularization, and collagen organization, as well as by the surface deterioration of the meshes.

CONCLUSION

In conclusion, results indicate that vitamin E coating reduces inflammatory response following hernioplasty and protects mesh material from oxidative deterioration.

Coelenterazine-Dependent Luciferases as a Powerful Analytical Tool for Research and Biomedical Applications

: The functioning of bioluminescent systems in most of the known marine organisms is based on the oxidation reaction of the same substrate-coelenterazine (CTZ), catalyzed by luciferase. Despite the diversity in structures and the functioning mechanisms, these enzymes can be united into a common group called CTZ-dependent luciferases. Among these, there are two sharply different types of the system organization-Ca2+-regulated photoproteins and luciferases themselves that function in accordance with the classical enzyme-substrate kinetics. Along with deep and comprehensive fundamental research on these systems, approaches and methods of their practical use as highly sensitive reporters in analytics have been developed. The research aiming at the creation of artificial luciferases and synthetic CTZ analogues with new unique properties has led to the development of new experimental analytical methods based on them. The commercial availability of many ready-to-use assay systems based on CTZ-dependent luciferases is also important when choosing them by first-time-users. The development of analytical methods based on these bioluminescent systems is currently booming. The bioluminescent systems under consideration were successfully applied in various biological research areas, which confirms them to be a powerful analytical tool. In this review, we consider the main directions, results, and achievements in research involving these luciferases.

Effect of the platelet-rich plasma covering of polypropylene mesh on oxidative stress, inflammation, and adhesions

INTRODUCTION AND HYPOTHESIS

Polypropylene mesh (PPM) is often used for urogynecological repair; however, it can cause complications. An approach to reduce complications is to coat PPM with anti-inflammatory and wound-healing molecules. Platelet-rich plasma (PRP) is inexpensive and improves wound healing. Therefore, we evaluated whether covering PPM with PRP could reduce inflammation, adhesion, and oxidative stress (OS) in rabbits.

METHODS

The primary objective was to evaluate OS, and the secondary objectives were to evaluate inflammation and adhesion. PRP-coated PPM was implanted on the right side of the abdominal cavity of 12 female New Zealand rabbits, in the interface between the hypodermis and peritoneum. An uncoverated PPM was implanted in the other side. Twelve rabbits served as the sham group; all animals were euthanized after 30 or 60 days. Inflammatory parameters were myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) activities. OS was evaluated by measuring the ferric-reducing antioxidant power, the free-radical-reducing ability of 3-ethylbenzothiazoline-6-sulfonic acid [2,2'-azino-bis (ABTS)], reduced glutathione levels, and superoxide anion production. Adhesion was measured using tenacity and Diamond scales (the latter of which grades adhesions according to their extent) Inflammation and OS were analyzed by analysis of variance (ANOVA), followed by Tukey's test. The Mann-Whitney test was used to evaluate adhesions, and analysis of the sham group was conducted using Kruskal-Wallis test.

RESULTS

No significant differences were observed in parameters of adhesions. After 60 days, PRP-coverated PPM presented a decrease in MPO and NAG activities. Furthermore, decreased OS and increased antioxidant levels were observed in PRP-coverated PPM samples.

CONCLUSIONS

The reduction of OS and inflammatory responses indicates that PRP-covered PPM is a promising therapeutic approach.

Anti-inflammatory coatings of hernia repair meshes: A pilot study

The current prevalence of postoperative chronic pain from hernioplasty procedures employing polymer mesh is close to 30%. Most of the researchers agree that oxidative stress, resulting from the release of oxidants and enzymes during acute inflammatory response, is a key factor in the development of posthernioplasty complications. This results in both the decrease of the biomechanical properties and stiffening of the polymer fibers of the mesh, leading to chronic pain. Moreover, enhanced activity of inflammatory cells can lead to an excessive deposition of connective tissue around the implant. In this study polypropylene hernia repair meshes coated with vitamin E (α-tocopherol), a known antioxidant, were prepared and characterized. The absorption isotherm of vitamin E on the mesh was characterized and a release profile study yielded a promising results, showing sustained release of the drug over a 10-day period. An animal study was conducted, and histological analysis five weeks after implantation exhibited a reduced host tissue response for a modified mesh as compared to a plain mesh, as evidenced by a higher mature collagen to immature collagen ratio, as well as lower level of fatty infiltrates, neovascularization and fibrosis in the case of modified mesh. These results support the use of α-tocopherol as a potential coating in attempt to reduce the extent of postoperative inflammation, and thereby improve long-term outcomes of hernioplasty. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 589-597, 2018.

Synthetic meshes in the treatment of postoperative fascial dehiscence of the spine

BACKGROUND

A fascial dehiscence after spinal instrumentation is usually located at the mechanically stressed interscapular thoracic spine and often causes cosmetic impairment and pain. However, therapy options remain barely discussed. Synthetic meshes have been successfully used in the treatment of abdominal hernias.

OBJECTIVE

It was hypothesized that synthetic meshes are a successful treatment option for spinal fascial dehiscence.

METHODS

This retrospective study of a prospective database investigated all consecutive patients who received a synthetic mesh for a fascial dehiscence of the spine between 2010 and 2014 after prior spinal instrumentation. Primary outcomes were healing of the fascial dehiscence, recurrence, infection, revision, subjective satisfaction on a visual analog scale (VAS), and the Oswestry Disability Index (ODI). Among others, secondary outcomes consisted of seroma formation and return to work. The evaluated risk factors consisted of the body mass index (BMI), outer abdominal fat (OAF), back tissue, smoking, immunomodulatory therapy, preoperative radiation dose, and instrumented levels.

RESULTS

Sixteen patients with a mean follow up of 24 months were included. Every fascial dehiscence successfully healed with the synthetic mesh and there were no recurrences, infections or revisions. The mean subjective satisfaction level was VAS 7.3 and the mean ODI was 26%. Five (31%) patients had a seroma postoperatively, but did not show any differences in the outcome (e.g. ODI of 28%). In the patient group < 65 years (n = 12), all but two patients, who had work restrictions due to other diseases, regained at least some capacity to work. Worse ODI scores were found for patients with increased BMI, OAF, back tissue, cortisone therapy, instrumented levels, preoperative radiation dose, and for smokers.

CONCLUSION

Synthetic meshes are a successful treatment option for spinal fascial dehiscence, even seemingly in patients with a higher risk profile such as obese and immunocompromised patients as well as in revision procedures. They are associated with respectable cosmetic results, pain relief and clinical outcome. Postoperatively, it is recommended to leave drains for more than five to seven days in order to avoid seroma formation and to avoid weight training for six weeks. Further prospective, comparative studies are recommended.

Transforming surgery through biomaterial template technology

Templates inserted into surgical wounds strongly influence the healing responses in humans. The science of these templates, in the form of extracellular matrix biomaterials, is rapidly evolving and improving as the natural interactions with the body become better understood.

Central failures of lightweight monofilament polyester mesh causing hernia recurrence: a cautionary note

INTRODUCTION

Uncoated, lightweight, macroporous,monofilament mesh has been shown to demonstrate improved bacterial clearance, better tissue integration,reduced foreign body response, and less chronic pain with equivalent durability for hernia repair. These findings led us to use a new lightweight monofilament polyester mesh (Parietex TCM, Covidien). Here, we report our experience with this mesh in open incisional hernia repair.

METHODS

Patients undergoing incisional hernia repair with Parietex TCM were retrospectively identified within our prospectively maintained database. Patient demographics,operative characteristics, and follow-up were reviewed. Outcome parameters included 90-day wound morbidity and hernia recurrence.

RESULTS

In 2011, 36 patients (mean age 56.8; mean BMI32.4 kg/m2) underwent open incisional hernia repair with retrorectus mesh placement by two surgeons (MJR, YWN) at Case Medical Center. Anterior and posterior fascial closure was achieved in all cases. Wound morbidity included seven surgical site occurrences: four superficial infections that resolved with antibiotics, one wound dehiscence requiring wet-to-dry packing, and two seromas that resolved without intervention. With a mean follow-up of 13 months, 8 (22%) recurrences have occurred. On reoperation, 7 (19%) of these patients had mechanical failure or fracturing of the mesh. No confounding variables were identified by univariate analysis of patient demographics,operative characteristics, or wound morbidity.

CONCLUSION

Lightweight monofilament polyester mesh (Parietex TCM) appears to have a high incidence of mechanical failure in the context of open incisional hernia repair. While this limitation may ultimately be revealed asa weakness of all lightweight mesh, surgeons should be aware that these failures have already been documented.

A review of biocompatibility in hernia repair; considerations in vitro and in vivo for selecting the most appropriate repair material

PURPOSE

Repair of hernia typically makes use of a prosthetic material; synthetic or biologic in nature. Any material which enters the body is subject to interrogation by the inflammation and immune system in addition to numerous other cell families, the outcome of which ultimately determines the success of the repair. In this review, we discuss the fundamental biology which occurs in situ when a biomaterial associates with a tissue, compare and contrast the techniques available to predict this in vitro, and review how features of hernia repair materials specifically may manipulate tissue interrogation and integration. Finally, we conclude our article by examining how biocompatibility impacts surgical practise and how a better understanding of the manner by which materials and tissues interact could benefit hernia repair.

MATERIALS AND METHODS

A review of the literature was conducted using appropriate scientific search engines in addition to inclusion of findings from the groups' primary research.

RESULTS

Using pre-clinical assays to anticipate the biocompatibility of a medical device is critical; however, to maximise the scientific power of in vitro findings, we must carefully consider the in vivo niche of the cells with which we are working. Excessive in vitro culture or contact to non-self materials can add compounding complexity to studies involving leucocytes for instance; therefore, we must ensure careful and stringent assay design when developing techniques for assaying pre-clinical biocompatibility. Furthermore, many of the features associated with hernia repair material design specifically, included to enhance their mechanical or biodegradation characteristics, are inadvertently instructive to cells, and therefore, throughout the prototype stages of a materials development, regular biocompatibility assessment must be performed.

CONCLUSION

The biocompatibility of a material is rate limiting in its ability to function as a medical device. The future of hernia repair materials will rely on close cohesion between the surgical and scientific communities to ensure the most robust biocompatibility assessment techniques, and models are utilised to predict the efficacy of a given material in a particular surgical application.

Porcine dermis implants in soft-tissue reconstruction: current status

Soft-tissue reconstruction for a variety of surgical conditions, such as abdominal wall hernia or pelvic organ prolapse, remains a challenge. There are numerous meshes available that may be simply categorized as either synthetic or biologic. Within biologic meshes, porcine dermal meshes have come to dominate the market. This review examines the current evidence for their use and the limitations of knowledge. Although there is increasing evidence to support their safety, long-term follow-up studies that support their efficacy are lacking. Numerous clinical trials that remain ongoing may help elucidate their precise role in soft-tissue reconstruction.

Preservation of aortic root architecture and properties using a detergent-enzymatic perfusion protocol

Aortic valve degeneration and dysfunction is one of the leading causes for morbidity and mortality. The conventional heart-valve prostheses have significant limitations with either life-long anticoagulation therapeutic associated bleeding complications (mechanical valves) or limited durability (biological valves). Tissue engineered valve replacement recently showed encouraging results, but the unpredictable outcome of tissue degeneration is likely associated to the extensive tissue processing methods. We believe that optimized decellularization procedures may provide aortic valve/root grafts improved durability. We present an improved/innovative decellularization approach using a detergent-enzymatic perfusion method, which is both quicker and has less exposure of matrix degenerating detergents, compared to previous protocols. The obtained graft was characterized for its architecture, extracellular matrix proteins, mechanical and immunological properties. We further analyzed the engineered aortic root for biocompatibility by cell adhesion and viability in vitro and heterotopic implantation in vivo. The developed decellularization protocol was substantially reduced in processing time whilst maintaining tissue integrity. Furthermore, the decellularized aortic root remained bioactive without eliciting any adverse immunological reaction. Cell adhesion and viability demonstrated the scaffold's biocompatibility. Our optimized decellularization protocol may be useful to develop the next generation of clinical valve prosthesis with a focus on improved mechanical properties and durability.

Evaluation of six synthetic surgical meshes implanted subcutaneously in a rat model

The long-term efficacy and mechanical integrity of implanted materials is largely determined by early host response. Therefore, implanting materials with well-characterized tissue responses provides the greatest chance of 'one-hit' surgical successes, without repeated interventions to replace, repair or remove non-compliant biomaterials. Six synthetic meshes were implanted subcutaneously in a rat model to deduce and quantify modulations in host response, based on material fabrication variables. The materials consisted of knitting variations of polypropylene (PP), polyethyleneterephthalate (PET) and polyglycolic acid (PGA) yarns and were implanted for 2, 5, 7, 14 and 28 days before fixation and both semi- and fully quantitative histopathology. In a subcutaneous niche, material weight did not influence foreign body response. PET stimulated earlier inflammation than PP and PGA, which normalized over 28 days. Multifilament meshes recruited foreign body giant cells, which were largely absent from monofilaments. Using CD68, PGA was demonstrated to be the greatest leukocyte-activating polymer at a number of the time points analysed. This research therefore highlights that underlying polymer composition may be more over-arching in deciding the inflammatory properties of surgical meshes, based on increased macrophagic responses to PGA vs alternative base polymers of comparable weights and porosities. Copyright © 2013 John Wiley & Sons, Ltd.

Coating with autologous plasma improves biocompatibility of mesh grafts in vitro: development stage of a surgical innovation

Purpose. To investigate mesh coating modalities with autologous blood components in a recently developed in vitro test system for biocompatibility assessment of alloplastic materials. Materials and Methods. Seven different mesh types, currently used in various indications, were randomly investigated. Meshes were coated prior to cultivation with autologous peripheral blood mononuclear cells (PBMCs), platelets, and blood plasma. Pretreated meshes were incubated over 6 weeks in a minced tissue assay, representative for fibroblasts, muscle cells, and endothelial cells originating from 10 different patients. Adherence of those tissues on the meshes was microscopically investigated and semiquantitatively assessed using a previously described scoring system. Results. Coating with peripheral blood mononuclear cells did not affect the adherence score, whereas coating with platelets and blood plasma increased the score suggesting improved biocompatibility in vitro. The previous ranking of native meshes remained consistent after coating. Conclusion. Plasma coating of meshes improves their biocompatibility score in a novel in vitro test system.

Characterization of poly-4-hydroxybutyrate mesh for hernia repair applications

BACKGROUND

Phasix mesh is a fully resorbable implant for soft tissue reconstruction made from knitted poly-4-hydroxybutyrate monofilament fibers. The objectives of this study were to characterize the in vitro and in vivo mechanical and resorption properties of Phasix mesh over time, and to assess the functional performance in a porcine model of abdominal hernia repair.

MATERIALS AND METHODS

We evaluated accelerated in vitro degradation of Phasix mesh in 3 mol/L HCl through 120 h incubation. We also evaluated functional performance after repair of a surgically created abdominal hernia defect in a porcine model through 72 wk. Mechanical and molecular weight (MW) properties were fully characterized in both studies over time.

RESULTS

Phasix mesh demonstrated a significant reduction in mechanical strength and MW over 120 h in the accelerated degradation in vitro test. In vivo, the Phasix mesh repair demonstrated 80%, 65%, 58%, 37%, and 18% greater strength, compared with native abdominal wall at 8, 16, 32, and 48 wk post-implantation, respectively, and comparable repair strength at 72 wk post-implantation despite a significant reduction in mesh MW over time.

CONCLUSIONS

Both in vitro and in vivo data suggest that Phasix mesh provides a durable scaffold for mechanical reinforcement of soft tissue. Furthermore, a Phasix mesh surgical defect repair in a large animal model demonstrated successful transfer of load bearing from the mesh to the repaired abdominal wall, thereby successfully returning the mechanical properties of repaired host tissue to its native state over an extended time period.